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JIMV
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Another rookie question

I am playing with my iMAC. I seldom use it as the rest of my computers are PC's. I have removed 90% of the programs and files from it and have installed Channel D Pure Music software...Now the question. It appears I can run a Toslink optical digital out from the iMAC. I need to run a Toslink cable maybe 25 ft to my DAC...I have never tied to run an optical cable so far...

I know the optical cables are less than optimum but my DAC only has an optical input unused. What is the limit for a Toslink conection??

Elk
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`

I bet you will be fine.

Buy a long Toslink from Monoprice.com and try it. They have 25 and 50 foot optical cables as I recall.

John Atkinson
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Maximum Length of Toslink optical link
JIMV wrote:
I am playing with my iMAC. I seldom use it as the rest of my computers are PC's. I have removed 90% of the programs and files from it and have installed Channel D Pure Music software...Now the question. It appears I can run a Toslink optical digital out from the iMAC. I need to run a Toslink cable maybe 25 ft to my DAC...I have never tried to run an optical cable so far...

Longest I have run is 15' of generic plastic Toslink. Depends on what source component you are using, but this gives about 3x the data-related jitter than a 1m length with my MacBook. Depends on what DAC you are using if this is going to be an issue or not.

John Atkinson
Editor, Stereophile

JIMV
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Benchmark DAC1

Benchmark DAC1

deathrage
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from a tech perspective

Now i am not a expert by any means when it comes to the audio field (im working on it) but from a technical perspective from a person who works with optical equipment every day i can offer this. If toslink follows any of the same rules as optical transmissions you should be fine, optical is known for its ability to transmit extreamly long distances without signal degregation and there is no chance of emenation or cross talk due to the nature of the transmition being optical rather than electrical. But from what i understand toslink uses plastic conductor and not actual "glass" as in true optical tech so there is a real limit to the transmition, the material is not "pure" like glass so it is like looking through a bathroom glass window, when stuff is close to the glass it looks clear, but the further someone stands from the glass the more hazy it gets. Maybe you can find a high end toslink cable that is made from glass and not plastic, you just have to be carefull becuase they can be fragile and cannot be bent severely for fear of cracking the glass conductor.

JIMV
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I understand the haze you

I understand the haze you note is measured in jitter. My DAC is reputed to be very tolerant of jitter, so I'll see. The cable is on order and, like so much of my mail at this time of the year, late.

deathrage
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checked my refreses

so i did a little research and found the technical limit for toslink cables made of glass is 33 ft before error correction becomes a problem, here is a 25ft glass toslink cable that should suit your aplication.

http://www.amazon.com/gp/product/B0037JCDXI/ref=pd_lpo_k2_dp_sr_3?pf_rd_...

JIMV
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Thanks for the suggestion..I

Thanks for the suggestion..I have a roll of home theater cable already on order but it was a small investment. I will try to set up the system with that and use your option as an upgrade path...

JIMV
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Well I have everything up and

Well I have everything up and running...The same song played as a WAV file/pure audio up-sampled to 24/96 through a 25ft cheap toslink cable, differs greatly from the same song played by my transport into the same DAC1 via an Audio Alchemy digital cable...

The computer based sound is more grainy, has less clear highs, and a poorer soundstage.

Assuming bits is bits, the only difference is in the cables. The 25ft cheap toslink sounds way worse then my ancient audio alchemy into the same DAC.

So, the question now is, would an actual glass Toslink cable sound better than the cheap plastic one I am now using...would I get less jitter?

Opinions anyone?

Elk
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~

I assume that you have checked to make sure the issue is the cable/connection. The computer files sound the same if they are sent to the DAC via a short Toslink or other short cable, yes?

How are you upsampling and why? The Benchmark (as with many DACs) upsamples as part of its conversion process in any event.

The long plastic cable may be an issue. As I understand optical cables, both the cable itself and the lenses at each end are important. At this length and price point you may have exceeded the capability of the cable.

But check to make sure you can get good sound out of the computer first if you haven't already. Also make sure the iMac isn't doing something to the file that you are unaware of.

JIMV
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The benchmark does not

The benchmark does not upsample, it simply recognizes upsampled files up to 24/96 (my version)...If I am wrong, please let me know. As to what is upsampling, the Pure Music software can upsample WAV files and I have set it to 24/96...The files DO sound better so routed to the DAC but the sound is still far worse than the sound from the transport.

I tried the cheapest bulk toslink I could find BUT have a glass cable on order (as recommended by Deathrage) that I hope will improve things. I hear cable changes with normal cables but have never played much with Toslink...

JIMV
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A quick thanks to Deathrage

A quick thanks to Deathrage for the glass Toslink suggestion. I was unhappy with the cheap (under $5) toslink cable I was using. I got music but worse than I was getting from my Sony $50DVD player in my most assuredly low tech/lo fi system in my living room. As our Editor noted, jitter could be a problem with a 25ft run. It (or something ) was. The sound was gritty and mushy at the same time.

I took Deathrage's recommendation and bought the actual glass cable he found. The sound was WAY better, still not as nice as from my transport but now it is more a standard toslink v other connector difference I was used to. The grit was gone and the muddy missing. The only significant difference is that acoustic instruments sound a tiny bit off..very tiny.

So, I now have a computer based system (when I want it) and like the sound.

A 'Christmas' plug...Try this soundtrack

http://www.amazon.com/Hot-Spot-Original-Picture-Soundtrack/dp/B0000047BA...

Look at who is on it and consider, this might be the best recorded music I have ever heard. If you can find the LP, grab it...it is an amazing bit of music. I heard this on a good vinyl based setup a few months ago and was blown away.

JIMV
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Tried a Grant Fidelity

Tube buffer...the grit is gone and the midrange is glorious BUT, I have a little less presence..The Grant is new and not broken in so I cannot make any call as to long term sound. In addition, I had to add another cable, a much more basic Kimber PBJ to hook up the tube buffer so any loss in sound could also be due to the cable...

I would like a short Transparent interconnect so as to keep the system sound as it was...Perhaps I can find something used.

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